<?php
/**
 * @package php-font-lib
 * @link    https://github.com/PhenX/php-font-lib
 * @author  Fabien Ménager <fabien.menager@gmail.com>
 * @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
 */

namespace isszz\captcha\font\lib\table\type;
use isszz\captcha\font\lib\table\Table;

/**
 * `hmtx` font table.
 *
 * @package php-font-lib
 */
class Hmtx extends Table
{
	protected function _parse()
	{
		$font   = $this->getFont();
		$offset = $font->pos();

		$numOfLongHorMetrics = $font->getData("hhea", "numOfLongHorMetrics");
		$numGlyphs           = $font->getData("maxp", "numGlyphs");

		$font->seek($offset);

		$data = [];
		$metrics = $font->readUInt16Many($numOfLongHorMetrics * 2);
		for ($gid = 0, $mid = 0; $gid < $numOfLongHorMetrics; $gid++) {
			$advanceWidth    = isset($metrics[$mid]) ? $metrics[$mid] : 0;
			$mid += 1;
			$leftSideBearing = isset($metrics[$mid]) ? $metrics[$mid] : 0;
			$mid += 1;
			$data[$gid]      = [$advanceWidth, $leftSideBearing];
		}

		if ($numOfLongHorMetrics < $numGlyphs) {
			$lastWidth = end($data);
			$data      = array_pad($data, $numGlyphs, $lastWidth);
		}

		$this->data = $data;
	}

	protected function _encode()
	{
		$font   = $this->getFont();
		$subset = $font->getSubset();
		$data   = $this->data;

		$length = 0;

		foreach ($subset as $gid) {
			$length += $font->writeUInt16($data[$gid][0]);
			$length += $font->writeUInt16($data[$gid][1]);
		}

		return $length;
	}
}